1. Technical Field
The present invention relates generally to information storage devices used with digital computers and, more particularly, to the use of storage interface bridges in conjunction with removable storage device assemblies.
2. Description of Related Art
Numerous computer applications require the storage and retrieval of large quantities of data, the bulk of which is stored on computer hard disks. Frequently, the amount of data to be stored exceeds the capacity of hard disks which are permanently attached to a computer; or the need for portability precludes the permanent attachment of hard disks to the primary or host computer.
In order to address the demand for portable hard disk storage, the computer industry has developed a number of schemes by which hard disks can be coupled to and removed from computers. On the one hand, certain computer interfaces, protocols, and associated software drivers have been developed which recognize and respond to the dynamic attachment and removal of devices including hard disks (that is, coupling and decoupling without the need for cycling through de-energizing and re-energizing/re-booting the device and/or host computer). IEEE 1394, also commonly known as FireWire, and SBP-2 are examples of one such interface and protocol, respectively. USB (Universal Serial Bus) and its related Mass Storage Class Protocol are each another example of such an interface and protocol, respectively. Hereinafter, interfaces, protocols and associated drivers which support the dynamic attachment and removal of devices including hard disks will be referred to collectively as “hot-swap interfaces.”
On the other hand, manufacturers also have developed physical mounting assemblies which facilitate the attachment and removal of computer hard disks. A component of such assemblies, sometimes referred to as a “bay,” is permanently mounted within a computer or disk storage enclosure. A second component of such assemblies, sometimes referred to as a “sled,” slides in and out of the bay as needed. The sled serves as a protective mount for a hard disk, and the hard disk may be permanently or temporarily mounted in the sled. An energization switch and/or other energization control, such as a mechanical key switch or the like, is often incorporated in the bay or sled. When engaged, this energization control simultaneously prevents the physical removal of the sled from the bay and energizes the hard disk mounted within the sled. Conversely, disengaging the switch de-energizes the hard disk, disables operation of the device and allows physical removal of the sled. A bay and its corresponding sled can be referred to collectively as a “drive bay.”
Drive bays typically present the same hard disk interface to the computer as is presented by the hard disk itself. Integrated/Intelligent Drive Electronics (IDE) and Serial Advanced Technology Attachment (SATA) are two examples of such hard disk interfaces, which are well known to those skilled in the art. Although drive bays are intended to facilitate the attachment and removal of IDE and SATA hard disks, the IDE and SATA disk interfaces (and the software drivers which control them) are not generally designed to support dynamic attachment and removal (that is, hot-swapping). Thus, use of most physical drive bays is limited to scenarios in which the entire primary/host computer is power-cycled or rebooted in order to recognize the attachment or removal (that is, coupling or de-coupling) of the hard disks mounted within the drive bays. Clearly, this greatly limits the flexibility and utility of removable hard disk storage.
A class of products called “bridges” have been used to translate between one or more hot-swap interfaces of a host computer and one or more IDE or SATA hard disk interfaces of a drive bay or the like. These bridges are most typically implemented as printed circuit board (PCB) assemblies which, along with a hard disk, are permanently mounted within a portable enclosure. The enclosure presents a hot-swap interface to a host computer, internally translating requests from the host computer to the format required by the IDE or SATA hard disk attached to the bridge. This has generally been a very successful solution and IEEE 1394 and USB storage devices are widely deployed.
Certain manufacturers have gone so far as to integrate such bridge functionality directly into specially built drive bays, thus allowing the drive bay itself present a hot-swap interface to the host computer. Unfortunately, the bridge PCB assemblies required to make this feasible are highly specialized, being mechanically and electrically limited to accommodate a specific drive bay design. As such, there is little choice with such integrated bridge/drive bay designs, often leaving no options for specific features or characteristics as may be required by individual applications. Moreover, the design of such integrated bridge/drive bay designs often precludes the coexistence of more than one such bridge/drive bay on a given hot-swap interface.
Portable bridges also have been developed and are in wide use, such as those manufactured and sold by Tableau, LLC. These devices require a power and operational scheme that ensures that both the drive bay and bridge are energized and the bridging function of the bridge enabled, which typically requires separate device activation by a technician by engaging the switch on the drive bay and enabling the bridge function of the bridge. Where multiple drive bays are to be accessible to a bridge, the power switches must be managed by the technician/user to ensure proper operation of the configuration/array.
Systems, methods and techniques that provide a simple means for connecting and hot-swapping various devices of this type would represent a significant advancement in the art. Also, systems, methods and techniques that allow a hard disk bridge to sense energization of a drive bay without the need for separate activation by a technician or the like likewise would represent a significant advancement in the art.